<em># 定义</em>
<i>Duration</i> <s>A</s> = <b>Duration</b>(days: 1, hours: 1, minutes: 1, seconds: 1, milliseconds: 1, microseconds: 1); 		<em>// => 25:01:01.001001</em>
<i>Duration</i> <s>B</s> = <b>Duration</b>(days: 2, hours: 2, minutes: 2, seconds: 2, milliseconds: 2, microseconds: 2);		<em>// => 50:02:02.002002</em>
<em># 加</em>
<i>Duration</i> v = <s>A</s> <b>+</b> <s>B</s>;		<em>// => 75:03:03.003003</em>
<em># 减</em>
<i>Duration</i> v = <s>A</s> <b>-</b> <s>B</s>;			<em>// => -25:01:01.001001</em>
<em># 乘</em>
<i>Duration</i> v = <s>A</s> <b>*</b> 2;			<em>// => 50:02:02.002002</em>
<em># 除</em>
<i>Duration</i> v = <s>A</s> <b>~/</b> 2;		<em>// => 25:01:01.001001</em>
<em># 比较</em>
<i>bool</i> v = <s>A</s> <b>></b> <s>B</s>;			<em>// => false</em>
<i>bool</i> v = <s>A</s> <b><</b> <s>B</s>;			<em>// => true</em>
<em># 取反</em>
<i>bool</i> v = <b>-</b><s>A</s> ;				<em>// => -25:01:01.001001</em>